Thiol-based Redox Sensing Regulates the Yellow Pigment and Antioxidants Accumulation and Improves the Nutritional Quality of Wheat Grains (Triticum aestivum L.)

Ranjeet Ranjan Kumar^1*Prashanth Babu H^1*Sumedha Hasija¹Mallesh Gampha¹Suneha Goswami¹Vinutha T¹Sudhir Kumar¹Gyan P Mishra¹Dwijesh Chandra Mishra²Gyanendra Kumar Rai³GIRISH JHA²SOORA NARESH KUMAR¹Shelly Praveen¹Aruna Tyagi¹Viswanathan Chinnusamy¹

• ¹Indian Agricultural Research Institute (ICAR), New Delhi, India
• ²Indian Agricultural Statistics Research Institute, Indian Council of Agricultural Research (ICAR), New Delhi, National Capital Territory of Delhi, India
• ³Faculty of Veterinary Sciences and Animal Husbandry, Sher-e-Kashmir University of Agricultural Sciences and Technology of Jammu, Jammu, Jammu and Kashmir, India

Thiol-based redox sensing has been characterized to play diverse roles in regulating various metabolic pathways. Here, sixteen diverse genotypes of wheat grains were characterized for thiol-based redox system and its correlation with accumulation of macro-/micronutrients inside the grains. We observed significant variations in the thiol and disulfide content in the grains.Expression analysis of genes responsible for thiol-based redox sensing like thioredoxin (TRX), glutaredoxin (GRX), and glutathione reductase (GR) showed maximum fold expression in wheat 2 cvs. Halna and HD2985 (high thiol cvs.) during seed hardening stage (G 2 ) of endosperm, as compared to low thiol containing cvs. We retrieved the amino acid sequences of 11 genes linked with nutrient biosynthesis pathways and observed maximum Cys (2.25%) in GBSS (involved in starch biosynthesis) and Met (4.04%) in BCH gene (involved in tannin synthesis). Genotypes with Cys: Met ratio >1.0 were observed to behave as nutrient-rich and robust due to the high stability of key proteins and enzymes. The yellow pigment (shining factor) was observed to be maximum in the grains of wheat cv. NIAW34 (6.08 µg/g dry matter) having a Cys:Met ratio of 2.15. Antioxidants like TPC and tannin were observed to be significantly higher in cvs. (Halna, HI1544, etc.) with a ratio of Cys:Met ≥2.0. The maximum polysaccharide (starch and resistant starch) was observed in the grains of wheat cv. HD1914 having Cys: Met ratio of 4.0. Results of the Pearson correlation indicated a negative relationship between thiol content and nutrient linked traits like total protein, gluten, and phytic acid. Micronutrients like iron and zinc showed a weak positive correlation with the thiol content. The role of thiol-based redox sensors needs to be further explored and utilized for manipulating the tolerance level and nutrient compositions of wheat grains. This will help in developing 'nutrient-smart grain' and 'climate-smart' crops with improved downstream processing and dough engineering.